The patent application relates to a wind turbine with a drive train of compact design.
Over the last decades, wind turbines have steadily grown in size, the trend being in the direction of ever more compact and more light-weight units. Here, so-called thrust bearings are quite often used that do not only absorb the thrust and transverse forces from the rotor but also transmit the bending moments at only one bearing location. Use of these bearings leads to markedly more compact drive trains compared with concepts having a double rotor bearing. However, in most cases of the known turbines, the gearboxes and also the generators are arranged behind the bearing as separate components on a main carrier. The main carrier then has the added function of transmitting the rotor loads from the rotor bearing into the nacelle. Since these thrust bearings have relatively large diameters and a two-dimensional stiff contact surface is required for bolting on over the entire circumference of the bearing, it is preferred to use main carriers of cast design. The loads then have to be introduced from the bearing bolting surface via the main carrier into the nacelle without the structure of the main carrier colliding with the gearbox and the generator. This leads to casting structures that require large openings in the area facing away from the rotor, for inserting the gearbox. These open structures have considerably disadvantages from the view-point of strength and deformations since the components experience large additional stresses as a result. Furthermore, these constructions have too many components since the function of the components is separate from the load transmission. The goal in the development of new wind turbines therefore has to be to design the turbines more compact, more light-weight, and more cost-effective.
WO 2005/033505 A1 shows a design of the drive train that is already very compact, having a separate gearbox and generator, where a large opening is provided for installing the gearbox. To fasten the generator, a further supporting structure is necessary becomes, a nacelle shroud is required to protect the components against climate influences.
DE 103 51 524 A1 likewise suggests a compact solution where it was possible to position the gearbox and the hub still closer together, the shaping of the casting structure of the main carrier is unfavorable, so that high tension peaks and deformations are to be expected. Here, too, a nacelle shroud is required.
With WO 02/079644 A1 a still more compact solution is suggested where part of the gearbox is being integrated into the rotor bearing. However, here too there is an additional gearbox and the separate generator that requires a further supporting structure. Furthermore the large opening can be seen in the cast main carrier, having considerable disadvantages in terms of structure.
DD 268741 A1 likewise shows a compact nacelle construction, this design being possible only for small wind turbines as the turbine is designed as a downwind machine and is equipped without a wind direction tracking unit and a vertical braking device. Furthermore the integration of gearbox and generator into a casing has the advantage of an extremely compact construction, but also the disadvantage that repairs can only be carried out with much effort as the possibilities for accessing the components is severely restricted.